Renal involvement in the Laurence-Moon-Biedl syndrome. Functional and radiological studies.

The renal abnormality of the Laurence-Moon-Biedl syndrome (LMBS) was investigated in six patients. The glomerular filtration rate (CIn) and the effective renal plasma flow (CPAH) were evaluated by standard clearance techniques and the single injection method, and the maximal concentration capacity was estimated by the ddAVP test. The kidney surface area and length were related to the body surface area, as well as the lumbar vertebrae L1-L3, and the relationship with the GFR was studied. All six patients showed renal abnormalities: Five had small kidneys with reduced GFR and concentrating ability, and one had hyperaminoaciduria (but normal kidney size). Two patients developed terminal renal failure (one of them was successfully transplanted), illustrating the progressive character of the renal lesion. Three of the patients had had recurrent urinary tract infections, but the radiological changes of the kidneys were of the same character as in the others (symmetrical and irregular parenchymal reduction, and blunting and clubbing of the calyces). Since renal abnormalities, with considerable risk for progression to terminal renal failure, are common in the LMBS, regular urine cultures and blood pressure measurements are probably of great importance.